I did these three images with Topaz Vivacity, Clean module.
I've had a lot of fun playing with it the last few days. An image with lots of detail works best for this effect. If you don't have enough detail, you can add noise with the Photoshop noise filter (that's what I did on the first image).
It works great on low-res images. I need to figure out how to get this effect on a high res image!
JD